From 044d95630556dda5492a70af056bc277f0b79ebc Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter@wuille.net>
Date: Wed, 20 Oct 2021 10:14:13 -0400
Subject: [PATCH] Fix G.y parity in sage code

---
 sage/secp256k1_params.sage | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sage/secp256k1_params.sage b/sage/secp256k1_params.sage
index 4e000726ed366..68f95adec4be7 100644
--- a/sage/secp256k1_params.sage
+++ b/sage/secp256k1_params.sage
@@ -9,6 +9,9 @@ C = EllipticCurve([F(0), F(7)])
 
 """Base point of secp256k1"""
 G = C.lift_x(0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798)
+if int(G[1]) & 1:
+    # G.y is even
+    G = -G
 
 """Prime order of secp256k1"""
 N = C.order()